Happy to consider a proposal / pull request which suggests how this should be presented.

@andypiper offtopic but I noticed data/apps.ts has links to the play store in an "android" category. Should I make a new category listing apps from F-Droid or add a new url?

Well, this is part of the issue here - I think it is straightforward to add a link to the main Mastodon app in the F-Droid store with a related button, but then having to do this across the other apps, without them showing up multiple times in multiple categories… this may require additional re-work. I am open to considering a solution, but I think it may need some experimentation and work to figure out what looks and works best.